A fuse or a fusible link is a portion of conductor interconnecting two or more regions of a semiconductor device, which can be severed under predetermined conditions. For example, when a sufficiently high current is passed through the conductor, the fuse will heat up and eventually melt, thereby “blowing” the fuse and severing the electrical connection between the semiconductor regions. In earlier DRAM generations, fuses were typically formed of aluminum or aluminum-copper alloys. More recently, fuses for integrated circuits (IC) are made from a variety of materials, such as polycrystaliine silicon, nichrome, or titanium-tungsten (TiW) alloys, among others.
Prior art methods for formation of either a vertical or a horizontal fuse typically involve several processing steps, which add to the processing time and expense of the manufacturing process. To minimize the additional processing steps the prior art has tried to integrate and/or associate the formation of the fuse elements with the formation of different conductive regions of a semiconductor substrate. For example, U.S. Pat. No. 4,598,462 teaches a fuse comprising platinum silicide associated with, and formed integral to, at least a well region. Similarly, U.S. Pat. No. 5,663,590 discloses a metallization process in which metal stringers are purposely left on sidewalls of a rectangular recess so that they can serve as fuses, which are then connected to one or more metal lines. None of these technologies, however, minimize the number of processing steps actually required to form the fuse.
Accordingly, there is a need for an improved method for fabricating an IC fuse which uses minimal processing steps.